Instrument for measuring the internal circumference of tires and like rings



Mar. 3, 1925. 1,528,315

, A. BARR ET AL INSTRUMENT FOR MEASURING THE INTERNAL CIRCUMFERENCE 0FTIRES AND LIKE RINGS Original Filed July 15, 1922 mm; ,1 iiiwwfwmwwmmwt.

Patented Mar, 3, 19255,

UNITED snares nnorrrnnnnunnna AND, WILLIAM s'r toon, F: GLASGOW,SCOTLAND, Ann; WALTER DE. LA. RoorIE BOND, or BIRMINGHAM, nnennrrn,nssrenor s, To BARB/AND srnoriio, LIMITED, or onessow, eoo'rLAnn.

INSTRUMENT ro a Mass-unmet,

Applicati'on filediJuly 15, 1322, Serial No 575,305. Renewed January 2,1925.

To all whom it may concern.- i

Be it known that WGL ARCHIBALD BARR anclflVILLIA r Srnopi), subjects; ofthe King of Great, Britain a n d Ireland, andibothof Caxton Street,Anniesland, Glasgow, Scotland, and" VALTER on "LA Room; Bonn, a subjectof the, King of GI'GELt-BIIttUH and' Ireland, and otf' FortlDunlop Erd ington,

B rmingham England, have invented new and useful Improvements inInstruments for llleasuring'the Internal circumferences of Tires andlike litings of which the,.fol lowing is a, specification;

This invention relates to means for measf uring the,internalcircumferences of rings, more especially of steel tires whichmay not be truly circular. V

Theobject of this inventionis to produce an instrumentof thev measuringdisc type oa pmnrisine e 2:

occupy f an approx mately central. osition Withiathe ri stQ Whichi hente na cumference is to bemeasured, a carrier on the support mounted toturnabout the axis thereof the carrier having means for supp rti g the masuri g dlsc arra ge to .mai tain' he a is oftli disc P r withtheaxisofthe, support and the rim of the r disc in one and the sameplane, and having means tending to thrust; the disc outvvards from theaxial support.

n e xamp e, o c n truct on the a -t uring di s c may be mounted upon afork or otherfldevice carried an arm sivivelling. a out he axial u po tand by m ns; ay, f r ne p i s) a fer e'is produ tend ng. tofthrust themeasur ng sc outwards from the ax al support and means are PlQVlQlQCl tom a ntail'r the .axls of the dlsc parallell to the axis ofthe axialsupport.

' n. he ire, t e ie nt d m, carr ing t e disc, is turneclabout the axialsupport so as to make one complete turn whereby some he eo the rwmfaenee. at t e is support, arranged to avlrere near the centre of thetire, a zero,

I again brought into contact with the position mark, when, from thereading of the disc,

the circumference of the tire may be deduced, note having beentaken ofthe number ofromplete revolutions ofthe disc.

To get the readings in millimetres, it is,

convenient to makev the circumferencev of the measuring disc an exactmultiple of lO-cms. (thus, e. g., it may he 10, 2O &o.,'cn1s.). As it.is not gfenerallydesirable that the measference of the measuring discmay be, say, -cms. or 60cms. or even more for aninstrument designediormeasuring tires for vehicles. 1

To read foif the total number of complete turns of the discspercircumferenceof a tire, a dial may be provided so geared to themeasuring disc that one revolution of the disc produces a fraction ofrevolution of tiring, disc should make many turns in cov erlng onerevolution of a tire, the circurn the dial. Thev dial maybeQsuitablynraduated and an indexprovided Thus, to read the internalcircumference of any ftire lying between 2 000 and 2,999-mnr, one startsWith the zero markof the dial opposite its index, and the zero mark ofthe measuring disc placed in coincidence With the position. mark on thetire, the jointed arm is then turned through ex actly one revolution sothat the periphery of the disc is againfin contact with the tire at theposition mark and record the first figure 2 (common to all the tiresconsidered), then the lower of the two; readings on the dial betweenwhich the dial index falls, then the; reading on the disc Opposite theposition mark 'asfan index. In addition to uniformly spaced graduap I Ktionsfbeingmarked on the measuring disc, To ea ulfetbe in erna circu fren e of, say, atlre, the t re may be laid upon a fiat standarchmarkscorresponding to certain standard sizes of tires in common use maybeprovided; and fi'irtherftoler'ance marks aboveand below the standardmarks may be provided to indicate the tolerances that may he, allowedbelowand above the standard sizes. One convenient ay of doing this is toprovide broad standard marks 'sof arranged that, if the tireis Withintheallowable tolerances, of the standardsize, this w ll be n ic ted by athe posit n m rk 9 the tire falling (after the measuring disc hasperformed one complete circuit of the internal circumference of thetire) within the limits of the broad standard mark. Such standard marksmay have engraved opposite them the standard diameter or circumferenceto which they relate.

An example of an instrument constructed according to this invention willnow be described with reference to the accompanying drawing in whichFigure 1 is a plan and Figure 2 is a broken sectional elevation. InFigure 2 the members of the jointed arm to be described are shownextended.

In the drawing the axial support illustrated comprises a heavy base Aprovided with a handle 1 fixed to the base by a shaft 2. Mounted to turnabout the shaft 2 is a sleeve 3 to which is fixed one end of a member B,the other end of B being fixed to a part 4 forming part of a swivellingjoint 4, 5, 6, 7, where 5 and 6 are two bushes fixed respectively to theparts 7 and 4, and 7 is a part to which is fixed one end of a member C.A jointed arm is thus formed comprising the members B and C. Between theparts 5 and 6 there is arranged a helical spring 8 in considerabletorsion, the direction of the torsional couplebeing such as to tend toincrease the size of the angle between the members B and C of thejointed arm. The outer end of the member C carries a case 9 within whichis mounted a measuring disc D supported on bearings about a spindle Dcarried by the case 9. Fixed to disc D is a toothed wheel 10 which gearswith the toothed rim of an index dial E, a portion of the surface ofwhich is visible through a window 11 in the case 9 the outside of whichis provided with an index mark 12.

In using the apparatus it is set up as shown in Figure 1, a positionmark designated 13 is made upon the inner surface of the tire F, and thedisc D is turned until the zero mark on the dial E is opposite the indexmark 12. This operation is carried out while the disc D is out ofcontact with the internal circumference of the tire F,

and when this operation is completed the disc D is placed into contactwith the tire F with the zero mark on the disc D exactly opposite themark 13 and is maintained in contact with the internal surface of thetire by the action of the spring 8. The case 9 may now be turned in thedirection of the arrow through one revolution about the shaft 2 when thereading upon the dial E and disc D will enable the magnitude of thecircumference to be read off.

The apparatus illustrated is portable and is intended to be used on ahorizontal surface. It can, however, be fixed and maybe used in avertical plane, in which casethe base A may be dispensed with and theshaft 2 may be fixed at the appropriate height, say, to a wall.

We claim:

1. An instrument of the measuring disc type comprising an axial support,a carrier on the support mounted to turnabout the axis thereof, ameasuring disc, means for supporting the measuring disc on the carrier,means for maintaining the axis of the disc parallel with the axis of thesupport and the rimof the disc in one and the same plane, and meanstending to thrust the disc outwards fromthe axial support, for thepurposes set forth.

2. An instrument of the measuring disc type comprising anaxial support,a jointed arm on the support mounted to turn about the axis thereof, abearing at the outer end of the jointed arm, a measuring disc supportedby the bearing, means for maintaining the axis of the disc parallel withthe axis of the support, and means tending to thrust the disc outwardsfrom the axial support, for the purposes set forth.

3. An instrument of the measuring disc type comprising an axial support,a jointed arm on the support mounted to turn about the axis thereof, thejointed arm comprising an inner member pivoted to the support and anouter member jointed to the-inner member, a hearing at the outer end ofthe outer member, a measuring disc supported by said bearing arranged tomaintain the axis of the disc parallel with the axis of the support andmeans tending to thrust the disc outwards from the axial support, forthe purposes set forth.

4. An instrument of the measuring disc type comprising an axial support,a jointed arm on the support mounted to turn about the axis thereof, thejointed arm comprising an inner member pivoted to the support, an outermember and a joint between the inner and outer members, a bearing at theouter end of the outer member, a measuring disc supported by saidbearing arranged to maintain the axis of the disc parallel with the axisof the support, and a spring in the joint between the members of the armtending to thrust the disc outwards from the axial support, for thepurposes set forth.

5. A portable instrument of the measuring disc type comprising an axialsupport having a heavy base, a carrier on the support mounted to turnabout the axis thereof, a measuring disc, means for supporting themeasuring disc on the carrier, means for maintaining the axis of thedisc parallel with the axis of the support and the rim of the disc inone and the same plane, and means tending to thrust the disc outwardsfrom the axial support, for the purposes set forth.

6. An instrument of the measuring disc type comprising an axial support,a carrier on the support mounted to turn about the axis thereof, ameasuring disc, means for supporting the measuring disc on the carrier,a dial index connected by gearing with the measuring disc, means formaintaining the axis of the disc parallel with the axis of the supportand means tending to thrust the disc outwards from the axial support,for the purposes set forth.

7. An instrument of the measuring disc type comprising an axial support,a carrier on the support mounted to turn about the axis thereof, abearing on the carrier, a measuring disc supported by the bearing, azero mark, uniform graduations and a standard mark or standard marks onthe measur ing disc, a dial index connected by gearing with themeasuring disc, means for maintaining the axis of the disc parallel withthe axis of the support and the rim of the disc in one and the sameplane, and means tend ing to thrust the disc outwards from the axialsupport, for the purposes set forth.

8. An instrument of the measuring disc type comprising an axial support,a jointed arm on the support mounted to turn about the axis thereof, thejointed arm comprising an inner member pivoted to the support, an outermember, and a joint between the inner and outer members, a bearing atthe outer end of the outer member, a measuring disc supported by thebearing arranged to maintain the axis of the disc parallel with the axisof the support, a dial index connected by gearing with the measuringdisc, a zero mark and graduation marks on the measuring disc, and aspring in the joint between the members of the arm tending to thrust thedisc outwards from the axial support, for the purposes set forth.

ARCI-IIBALD BARR.

lVILLIAM STROUD.

WALTER DE LA ROCHE BOND.

